The invention relates to flywheels and windpower machines which utilize fylwheels. The prior art includes a number of wind-power machines such as the picturesque windmill. Despite the advent of superior bearings and some technological advances in such apparatus it has been found that angular velocity of such apparatus continues to change radically with varying air currents. Accordingly it is a primary object of the invention to provide apparatus which will utilize the wind current and which will provide a relatively stable angular velocity to a shaft driven thereby to permit maximum utilization of the mechanical energy available.